It is a kind of that winding permanent magnet motor current predictive control method is opened based on virtual vector
Technical field
The present invention relates to electric system and control field more particularly to a kind of winding permanent magnet motor is opened based on virtual vector
Current predictive control method.
Background technique
Opening winding electric machine is to open the neutral point of conventional three-phase motor, constitutes the open knot of winding with dual-port
Structure, the magnetic circuit and structure of motor do not change, and open the basic performance that winding construction motor does not change conventional motors, and due in
Property point open after the constraint relationship between each phase machine winding no longer exist, each phase winding is independent, can be to a certain extent
Improve the reliability of motor body and the fault-tolerant ability of motor driven systems.Two ports of motor are respectively connected to current transformer, lead to
The current transformer coordinated control of two-port is crossed, can preferably meet high-power electricity in power distribution to two current transformers
Demand of the machine system to current transformer, therefore the research for opening winding electric machine control technology becomes important the opening up of current alternating current generator research
Open up direction.Currently, open winding permanent magnet Synchromous machine drive system because have both traditional permanent magnet synchronous motor high power density, efficiently
Rate, high performance feature and the advantages of open winding electric machine, have become the new direction of electric system development.
According to the difference of the connect current transformer power supply mode in port both ends, single electricity can be divided by opening winding permanent magnet motor drive system
The common DC bus type of source power supply and two kinds of topological structures of isolated form of dual power supply.Compared with isolated form structure, total direct current
Bus type structure is used widely because of its lower cost and lesser volume.In the class formation, due to current transformer, motor
It is formed into a loop with DC bus, zero-sequence current can be formed in the loop when current transformer output voltage contains common mode component, this meeting
It causes damages to motor shaft and switching device, therefore in the control for opening winding electric machine, the inhibition to common-mode voltage is a weight
Want content.
Winding permanent magnet motor is opened at present and mostly uses vector controlled, and this method is based on zero vector to the inhibition of common-mode voltage and divides again
With principle, common-mode voltage inhibitory effect is related with zero vector action time, to obtain comparatively ideal inhibitory effect, needs suitably to increase
Big DC side busbar voltage, and the Space Vector Modulation Strategy structure used in vector controlled is complex.
PREDICTIVE CONTROL is a kind of control algolithm risen in recent years.This method be based on controlled model to system future behaviour into
Row prediction, in conjunction with system history information, the control method of control amount is obtained by Rolling optimal strategy.Compared to conventional vector control
System, this method structure is relatively simple, in addition, the evaluation function in PREDICTIVE CONTROL can flexibly be formed according to system restriction, this makes
PREDICTIVE CONTROL has the ability of processing multiple constraint problem.Therefore PREDICTIVE CONTROL is opening answering in winding permanent magnet motor drive system
Play a significant role with to simplified control system structure.
Traditional PREDICTIVE CONTROL is to inhibit out winding permanent magnet electric by adding common-mode voltage inhibition item in evaluation function
Common-mode voltage in machine drive system, but this method is soft-constraint, can not thoroughly eliminate common-mode voltage, and in this method
Switching frequency is not fixed, this is also that the design of system brings certain difficulty.Therefore winding electric machine is being opened in the control of research Optimization Prediction
In application winding permanent magnet motor control performance opened to raising be of great significance.
Summary of the invention
The present invention provides a kind of to open winding permanent magnet motor current predictive control method, the present invention gram based on virtual vector
It has taken tradition and has opened that switching frequency in winding permanent magnet motor PREDICTIVE CONTROL is not fixed, common-mode voltage inhibitory effect is to be improved etc. no
Foot, described below:
A kind of to open winding permanent magnet motor current predictive control method based on virtual vector, the control method includes following
Step:
In order to eliminate common-mode voltage, casts out the switch combination containing common-mode voltage and part zero vector switch combination, obtain
Voltage vector without common-mode voltage;
Using the voltage vector without common-mode voltage of screening, amplitude is synthesized with load variation, direction and effective vector phase
6 same virtual vectors;
Switch function is formed by 7 inherent vectors and 6 virtual vectors;The switch function need to pass through virtual vector tune
Link processed obtains switch combination;
The evaluation function for obtaining the switch function being only made of current error item is chosen optimal according to 13 kinds of evaluation function values
Switch function;
Optimum switching function is generated to switching signal after external Virtual Vector Modulation and is applied to system, can be realized pair
While current control, stable switch frequency.
Wherein, the step of synthesis amplitude is with load variation, identical with effective vector 6 virtual vectors in direction is specific
Are as follows:
Load factor t controls the action time of zero vector and effective vector in the single sampling period, and then controls virtual arrow
The amplitude of amount.
Wherein, the virtual vector is indicated with load factor t are as follows:
uref=(1-t) uOH
Wherein, urefReference voltage value when for stable state, uOHFor the amplitude of voltage vector OH.
Further, the step of switch function need to obtain switch combination by virtual vector modulation link specifically:
According to the corresponding switching function value of virtual vector, the modulation to virtual vector is realized using isosceles triangle.
The step of modulation realized using isosceles triangle to virtual vector specifically:
After 6 components of switch function are by modulation, 6 components of switch combination are respectively corresponded;
When a certain switch function component value is more than or equal to triangular carrier, corresponding switch combination component output is 1;
When a certain switch function component value is less than triangular carrier, corresponding switch combination component output is 0.
Further, the evaluation function of the switch function specifically:
gm=[id,ref(k)-id,pre,m(k+2)]2+[iq,ref(k)-iq,pre,m(k+2)]2
In formula, gmIt is by switch function Sk,m(k+1) the evaluation function value obtained;id,ref(k) and iq,ref(k) join for electric current
Examine value, id,pre,m(k+2) and iq,pre,mIt (k+2) is k+2 moment current forecasting value.
The beneficial effect of the technical scheme provided by the present invention is that: this method uses the current forecasting control containing virtual vector
System, casts out space vector modulation link, has selected the smaller virtual vector modulation link of calculation amount.It is predicted compared to conventional current
Control, this method can simplify system knot while realizing that current control and common-mode voltage inhibit, stable switch frequency
Structure enhances system reliability.
Detailed description of the invention
Fig. 1 is to open winding permanent magnet motor predictive current control structure chart based on virtual vector;
Fig. 2 is the schematic diagram that each current transformer generates voltage vector and twin voltage Vector modulation;
Wherein, figure (a) and figure (b) are the voltage vector u that two current transformers generate respectivelys1And us2Distribution map, (c) table
Show that double convertor generates the schematic diagram of voltage vector synthesis.
Wherein, the voltage vector u that double convertor system generatessIt is considered as voltage arrow obtained by two current transformer independent roles
The superposition of amount, i.e. us=us1- us2。usSwitch combination be denoted as Sabc(Sabc,a1Sabc,b1Sabc,c1Sabc,a2Sabc,b2Sabc,c2), such as
Scheme (c) shown in, when 1 output voltage space vector of current transformer be 1, switch combination signal Sabc,a1、Sabc,b1、Sabc,c1Respectively
"1","0","0";2 output voltage space vector of current transformer is 3 ', switching tube output signal Sabc,a2、Sabc,b2、Sabc,c2Respectively
When " 0 ", " 1 ", " 0 ", two current transformer resultant voltage space vectors are 13 '.
Fig. 3 is the space voltage vector distribution map generated when double convertor is powered;
Wherein, OO, OA, OB ... OS are the voltage vector generated when double convertor is powered.Converter switches combination and electricity
The corresponding relationship of pressure vector is shown in Table 1.
Fig. 4 is virtual vector modulation principle figure;
Wherein, Sa1、Sb1、Sc1、Sa2、Sb2、Sc26 components of respectively switch function S, Sabc,a1、Sabc,b1、Sabc,c1、
Sabc,a2、Sabc,b2、Sabc,c2Respectively switch combination SabcComponent.In the present invention, switch function S has to pass through virtual vector tune
Link processed obtains switch combination SabcSystem can be just applied to.
Fig. 5 this method applied voltage vector set distribution map.
Difference switch combination and space voltage vector u when table 1 is double convertor power supplysAnd its common-mode voltage corresponds to table;
Table 2 is the switch function table of virtual vector;
Table 3 is voltage vector collection switch function table used in this method.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiment of the present invention is made below further
Ground detailed description.
It opens winding permanent magnet motor drive system to power using double convertor, entire control system is by speed outer ring and electric current
Ring is constituted.The single raw 8 kinds of switching groups of three bridge arm common properties of current transformer amount to corresponding 7 kinds of voltage vectors, and (1 zero vector, 6 effectively
Vector), the raw 64 kinds of switching groups of double convertor power supply common property amount to corresponding 19 voltage vectors, and (1 zero vector, 18 are effectively sweared
Amount), every kind of switch combination contains different common-mode voltages.The speed outer ring of system is made of PI controller, it can be according to reality
Border revolving speed and given rotating speed generate q shaft current reference value iq,ref, d shaft current reference value id,refThen and i given by outsided,ref=
0。
Current inner loop uses finite state predictive controller, in traditional controller evaluation function containing current error item and
Common-mode voltage inhibits item, and every kind of switch combination all corresponds to an evaluation function value, then makes the smallest switch combination of evaluation function value
This switch combination is applied in system and achieves that and inhibit common-mode voltage while current control by as optimum combination.But
This common-mode voltage bound term of adding in evaluation function inhibits the method binding character of common-mode voltage not strong, can not thoroughly eliminate
Common-mode voltage.
Embodiment 1
It is a kind of that winding permanent magnet motor current predictive control method is opened based on virtual vector, referring to Fig. 1, this method include with
Lower step:
101: in order to eliminate common-mode voltage, cast out the switch combination containing common-mode voltage and part zero vector switch combination,
Obtain the voltage vector for being free of common-mode voltage;
Filter out 20 kinds of switch combinations without common-mode voltage altogether through the above steps, which is divided into 2 groups,
Every group of correspondence 6 effective 1 zero vector of vector sum, this 6 effective 1 zero vector of vector sum are as 7 inherent vectors.
102: using the voltage vector without common-mode voltage screened, synthesis amplitude is with load variation, direction and effective arrow
Measure identical 6 virtual vectors;Switch function is formed by 7 inherent vectors and 6 virtual vectors;Switch function need to be by void
Quasi- Vector Modulation link obtains switch combination;
In the synthesis process of virtual vector, load factor t controls the work of zero vector and effective vector in the single sampling period
With the time, and then control the amplitude of virtual vector.
Wherein, switch function need to obtain switch combination S by virtual vector modulation linkabcThe step of specifically: according to void
The quasi- corresponding switching function value of vector realizes the modulation to virtual vector using isosceles triangle.
Current control accuracy is not only increased by the processing of the step 102, and stabilizes system switching frequency.
103: obtaining the evaluation function for the switch function being only made of current error item, chosen according to 13 kinds of evaluation function values
Optimum switching function;
Wherein, current error item specifically: the difference between current reference value and current forecasting value.
By the processing of step 103, totally 13 kinds of evaluation function values can be generated, selection makes the smallest switch letter of evaluation function value
Number is used as optimum switching function S (k+1).
104: optimum switching function S (k+1) being generated to switching signal after external Virtual Vector Modulation and is applied to system
While can be realized to current control, stable switch frequency.
In conclusion 101- step 104 can realize current control and common mode to the embodiment of the present invention through the above steps
Voltage inhibit while, stable switch frequency, simplify system structure, enhance system reliability.
Embodiment 2
Further it is situated between below with reference to specific calculation formula, table 1- table 3, Fig. 2-Fig. 5 to the scheme in embodiment 1
It continues, described below:
1 double convertor of table is powered the space voltage vector u synthesized under different switch combinationssAnd its common-mode voltage amplitude
It can be seen that voltage vector when double convertor is powered from table 1 and Fig. 3 and correspond to a variety of switch combinations, switch combination is deposited
In redundancy, in order to eliminate common-mode voltage, casts out the switch combination containing common-mode voltage and part zero vector switch combination, will be left
The inherent vector of non-common mode voltage be divided into 2 groups:
First group: 1 zero vector [88 ' (1 1111 1)];6 non-zero vectors [24 ' (1 1001 1)], [26 '
(1 1 0 1 0 1)],[46′(0 1 1 1 0 1)],[42′(0 1 1 1 1 0)],[62′(1 0 1 1 1 0)],[64′
(1 0 1 0 1 1)]。
Second group: 1 zero vector [77 ' (0 0000 0)];6 non-zero vectors [15 ' (1 0000 1)], [35 '
(0 1 0 0 0 1)],[31′(0 1 0 1 0 0)],[51′(0 0 1 1 0 0)],[53′(0 0 1 0 1 0)],[13′
(1 0 0 0 1 0)]。
In every group of voltage vector, on-off times when any non-zero vector state switches in zero vector and the group are all solid
Definite value.Therefore using the vectorial combination at stable on-off times can be generated when virtual vector.In actually control, optional one group
For base vector.This method use first group for base voltage vector (when specific implementation, can also use second group for base voltage
Vector, the embodiment of the present invention are without limitation).It is by base voltage Vector modulation virtual vector OH ' of first group of vector below
Example illustrates composition principle.
The amplitude of virtual vector is determined by motor load state.Using track with zero error principle, according to the dynamic side of motor
Journey calculates the corresponding voltage vector magnitude of load condition, the i.e. amplitude of virtual vector.
Open the voltage equation of winding electric machine are as follows:
In formula, idAnd iqFor dq shaft current, RsFor stator armature resistance, LdAnd LqIt is dq axle inductance, u respectivelydAnd uqIt is fixed
Sub- winding dq shaft voltage, ψdAnd ψqIt is dq axis magnetic linkage, ωrFor rotor angular rate.
Flux linkage equations are as follows:
In formula, ψrFor rotor flux.
Torque equation are as follows:
In formula, npIt is number of pole-pairs.
In the present system, d shaft current idReference value id,refFor 0, q shaft current iqReference value iq,refIt is given by external speed ring
It is fixed.When system is in steady-state operating condition, it is believed that the effective follow current reference value of inner ring electric current loop has at this time
In formula, Te,refTo give electromagnetic torque.(2) formula is substituted by formula (4) and derivation obtains:
Above formula (2), (3), (4) and (5) are substituted into reference voltage value u when abbreviation in voltage equation (1) obtains stable stateref:
In formula, ωr,refIt is external given rotating speed.
In the space voltage vector distribution map that double convertor shown in Fig. 3 generates when powering, the amplitude of voltage vector OH
uOHWith DC voltage VdcIt is related, it is calculated by following formula
Load factor t is defined,
Then the amplitude of virtual vector is expressed as with t
uref=(1-t) uOH (9)
In the synthesis process of virtual vector, load factor t controls the work of zero vector and effective vector in the single sampling period
With the time, and then control the amplitude of virtual vector.
Modulation for virtual vector OH ', the base vector used are [88 ' (1 1111 1)] and [24 ' (1 100
1 1)], the switching function value of virtual vector OH ' is [OH ' (1 1t t 1 1)] at this time, and this method uses isosceles triangle tune
System, modulated process are as shown in Figure 5.6 component (S of switch function Sa1、Sb1、Sb2、Sc2、Sc1、Sa2) by right respectively after modulation
Inductive switch combination Sabc6 component (respectively Sabc,a1、Sabc,b1、Sabc,c1、Sabc,a2、Sabc,b2、Sabc,c2).Work as switch function
When component is more than or equal to triangular carrier, the output of switch combination component is 1.
As shown in figure 5, being modulated by isosceles triangle, S in figurea1、Sb1、Sb2、Sc2It is all larger than in entire Ts equal to triangle
Carrier wave, at this time Sabc,a1、Sabc,b1、Sabc,b2、Sabc,c2Output is 1 in entire Ts.Sb2、Sc2Value is t (0≤t≤1), at this time
In tTsTo (1-t) TsIt is less than triangular carrier in period, at this time Sabc,c1、Sabc,a2Output is 0 during this period of time.In this way in Ts
Direct action vector (1 1111 1), (1 1001 1), (1 1111 1) in time can be realized to virtual arrow
Measure the synthesis of OH '.
Similarly, the switching function value S of other virtual vectors can be write out, as shown in table 2.
The switching function value S of each virtual vector of table 2
Virtual vector |
Switching function value S |
Base vector |
OH′ |
(1 1 t t 1 1) |
(1 1 1 1 1 1)(1 1 0 0 1 1) |
OJ′ |
(1 1 t 1 t 1) |
(1 1 1 1 1 1)(1 1 0 1 0 1) |
OL′ |
(t 1 1 1t 1) |
(1 1 1 1 1 1)(0 1 1 1 0 1) |
ON′ |
(t 1 1 1 1t) |
(1 1 1 1 1 1)(0 1 1 1 1 0) |
OQ′ |
(1 t 1 1 1t) |
(1 1 1 1 1 1)(1 0 1 1 1 0) |
OS′ |
(1 t 1 t 1 1) |
(1 1 1 1 1 1)(1 0 1 0 1 1) |
The intrinsic base vector of system and the virtual vector vector set that has collectively constituted system in this way, the vector set after simplifying are total
It is measured comprising 13, as shown in table 3, the distribution of voltage vector collection is as shown in Figure 5.
Voltage vector collection switch function table used in 3 this method of table
When specific implementation, computing relay is commonly present in system, in order to overcome delay bring to influence, this method is using as follows
Method eliminate delayed impact, the current controller course of work is as follows:
Converter switches function S and output voltage vector usRelationship are as follows:
In formula, Sa1、Sb1、Sc1、Sa2、Sb2、Sc2Indicate 6 components of converter switches function S, VdcFor DC voltage.
It is delayed since system exists, the k moment is applied to the voltage vector u of systemsIt (k) can be by Sk-1(k) according to formula (11)
It obtains, it may be assumed that
us(k)=f [Sk-1(k),Vdc(k)] (11)
In formula, VdcIt (k) is k moment DC voltage measured value, Sk-1It (k) is the switch function being calculated at the k-1 moment
Value.
If uds(k)、uqs(k) u is respectively indicateds(k) dq axis component, then k+1 moment electric current id,js(k+1) and iq,js(k+
1) are as follows:
In formula, id,cl(k) and iq,cl(k) k moment i is respectively indicateddAnd iqMeasured value, id,js(k+1) and iq,js(k+1) divide
Not Biao Shi k+1 moment calculated value, ωrIt (k) is k moment rotor angular rate, TsFor the sampling period.
In the method, totally 13 groups of system switching function, every kind of switch function and voltage vector corresponding relationship are as follows:
us,m(k+1)=f [Sk,m(k+1),Vdc(k)] (13)
In formula, Sk,m(k+1) switch combination to be assessed for the k+1 moment, us,mIt (k+1) is by Sk,m(k+1) voltage obtained
Vector, the constant that m is 1 to 13, represents 13 groups of switching function values.
If uds,m(k+1) and uqs,m(k+1) u is respectively indicateds,m(k+1) dq axis component.Then k+2 moment current forecasting value
id,pre,m(k+2) and iq,pre,m(k+2) are as follows:
To guarantee the lesser current error of system, the evaluation function setting of system are as follows:
gm=[id,ref(k)-id,pre,m(k+2)]2+[iq,ref(k)-iq,pre,m(k+2)]2 (15)
In formula, gmIt is by switch function Sk,m(k+1) the evaluation function value obtained;id,ref(k) and iq,ref(k) join for electric current
Examine value;id,pre,m(k+2) and iq,pre,mIt (k+2) is k+2 moment current forecasting value.
Totally 13 kinds of evaluation function values can be generated in this way, and selection makes the smallest switch function of evaluation function value as optimized switching
Function S (k+1), S (k+1) is generated to switching signal after external Virtual Vector Modulation being applied to current transformer can be realized to electricity
Stable switch frequency while flow control.
Wherein, optimum switching function S (k+1) is produced into switching signal, the present invention through above-mentioned virtual vector modulation
Embodiment repeats no more this.
In conclusion present example can inhibit same realizing current control and common-mode voltage by aforesaid operations
When, stable switch frequency, simplify system structure, enhance system reliability.
The embodiment of the present invention to the model of each device in addition to doing specified otherwise, the model of other devices with no restrictions,
As long as the device of above-mentioned function can be completed.
It will be appreciated by those skilled in the art that attached drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention
Serial number is for illustration only, does not represent the advantages or disadvantages of the embodiments.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.